You'd have been better asking this in Technical Help as it's not really anything to do with the PS3. Simply insert it into your PC, and download and run this tool to format the USB device:
Be careful not to format your computers disk drive by accident! 
Level 2
Nice 1 strangeplaice, personally l'd have passed it up since mr impatient thinks that no replies in under 2 hrs means we're all a bunch of selfish t**ts. When the reality is we just hadn't got to read & respond to his original post.
Next time post in correct thread matey if you want urgent response, & formatting a usb stick is hardly urgent when there are other options available for such matters
In the 2 hrs you waited l could have researched (as could you) the relevant info from the web 10 times over, you might like to bear that in mind for future reference. A thing called google or ask are great places to start. You might also try saying THANKS to strangeplacie for his help, or is that the last time you'll be needing assistance here???
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